JP2015044201A - Water treatment method and water treatment device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a water treatment method highly purifying industrial waste water or the like, thus suppressing the propagation of bacteria, and also capable of obtaining more impurity-free reutilizable permeable water.SOLUTION: Provided is a water treatment method including: a reduction step of reducing sterilization effective components in raw water to obtain reduced water; an ion exchange step of removing anions included in the reduced water to obtain anion exchange treatment water; and a reverse osmosis membrane treatment step of treating the anion exchange treatment water with a reverse osmosis membrane to obtain permeable water.

Description

  The present invention relates to a water treatment method and a water treatment apparatus.

A method of highly purifying industrial waste water and the like to obtain water free of impurities has been proposed.
For example, Patent Document 1 describes a method for treating peracetic acid-containing water, wherein the peracetic acid-containing water is brought into contact with activated carbon and then contacted with an anion exchange resin. According to this document, it is described that peracetic acid can be efficiently removed from peracetic acid-containing water to achieve water recovery and effective use.
For example, Patent Document 2 discloses a peracetic acid-containing wastewater treatment apparatus that contains a peracetic acid reduction catalyst and decomposes peracetic acid in peracetic acid-containing wastewater to be supplied into acetic acid. And a biological treatment unit that is supplied with acetic acid-containing water from the peracetic acid decomposition unit and decomposes the acetic acid by biological treatment. With a simple treatment apparatus, it is possible to carry out decomposition and removal of peracetic acid, and further, removal or decomposition of acetic acid generated after the decomposition of peracetic acid. As a result, treated water discharged from the treatment apparatus is It is described that it can be reused for factory water and domestic water, and water resources can be used effectively.

JP 2001-129564 A JP 2001-170657 A

  However, in the conventional methods described in Patent Documents 1 and 2, it cannot be said that the concentration of impurities contained in the obtained treated water is sufficiently low, and the inside of the treatment apparatus tends to be a hotbed of bacteria, and the bacteria flow out into the treated water. There was room for improvement.

  The present invention aims to solve the above-described problems. That is, an object of the present invention is to provide a water treatment method and a water treatment apparatus capable of highly purifying factory wastewater and the like to obtain permeate having a lower impurity concentration and a smaller number of bacteria.

The inventor has intensively studied and completed the present invention.
The present invention includes the following (1) to (8).
(1) a reduction step of reducing the sterilizing active ingredient in the raw water to obtain reduced water;
An ion exchange step of removing anion contained in the reduced water to obtain anion exchange treated water;
A water treatment method comprising: a reverse osmosis membrane treatment step of obtaining permeated water by treating the anion exchange treated water with a reverse osmosis membrane.
(2) an addition step of adding an ionic body-forming substance that forms an ionic body by combining with an uncharged organic substance that is an organic compound having no charge to raw water to obtain added water;
A water treatment method comprising: a reverse osmosis membrane treatment step of obtaining permeated water by treating the added water with a reverse osmosis membrane.
(3) an addition step of adding an ionic body-forming substance that forms an ionic body by combining with an uncharged organic substance, which is an organic compound having no charge, to the reduced water and / or the anion exchange treated water;
The water treatment method according to (1), wherein in the reverse osmosis membrane treatment step, the permeated water from which the uncharged organic matter is further removed is obtained.
(4) The reduction step includes
Using a reducing device comprising a first reaction tank and a second reaction tank filled with a reducing agent, and a communicating part connecting the upper ends of these tanks,
The raw water is passed upwardly into the first reaction tank, and the raw water that has flowed out from the upper end of the first reaction tank is caused to flow into the second reaction tank through the communication part, and the second reaction is performed. In the tank, the raw water is passed downward to obtain the reduced water discharged from the lower part of the second reaction tank [α],
The raw water is allowed to flow upward into the second reaction tank, and the raw water that has flowed out from the upper end of the second reaction tank is caused to flow into the first reaction tank through the communication portion, so that the first reaction is performed. In the tank, the raw water is passed downward, and the two processes of the process [β] for obtaining the reduced water discharged from the lower part of the first reaction tank are alternately performed (1) or (3 ) Water treatment method.
(5) a reducing unit that reduces the sterilizing active ingredient in the raw water to discharge reduced water;
An ion exchange unit that receives the reduced water, removes anions contained in the reduced water, and discharges the anion exchange treated water;
A water treatment apparatus comprising: a reverse osmosis membrane treatment unit for treating the anion exchange treated water with a reverse osmosis membrane and discharging permeated water.
(6) an addition means for adding an ionic body-forming substance that forms an ionic body by combining with an uncharged organic substance that is an organic compound having no charge to obtain added water;
The water treatment apparatus which has a reverse osmosis membrane process part which processes the said addition water with a reverse osmosis membrane, and obtains permeated water.
(7) It further has an addition means for adding an ionic body-forming substance that forms an ionic body by combining with an uncharged organic substance that is an organic compound having no charge to the reduced water and / or the anion exchange treated water. ,
The water treatment device according to (5), wherein the reverse osmosis membrane treatment unit further obtains the permeated water from which the uncharged organic substances are removed.
(8) The reducing unit is
A reduction device having a first reaction tank and a second reaction tank filled with a reducing agent, and a communication part connecting the upper ends of these tanks,
The raw water is passed upwardly into the first reaction tank, and the raw water that has flowed out from the upper end of the first reaction tank is caused to flow into the second reaction tank through the communication part, and the second reaction is performed. In the tank, the raw water is passed downward to obtain the reduced water discharged from the lower part of the second reaction tank [α],
The raw water is allowed to flow upward into the second reaction tank, and the raw water that has flowed out from the upper end of the second reaction tank is caused to flow into the first reaction tank through the communication portion, so that the first reaction is performed. In the tank, the raw water is allowed to flow downward, and the two processes [beta] for obtaining the reduced water discharged from the lower part of the first reaction tank can be alternately performed. The water treatment device according to (5) or (7) above.

  According to the present invention, it is possible to provide a water treatment method and a water treatment apparatus capable of highly purifying factory wastewater and the like and obtaining permeate having a lower impurity concentration and a smaller number of bacteria.

It is the schematic for demonstrating the water treatment method of the aspect 1 of this invention. It is the schematic for demonstrating the water treatment method of the aspect 2 of this invention. It is the schematic for demonstrating the water treatment method of aspect 3 of this invention. It is a schematic sectional drawing for demonstrating a preferable reduction | restoration part. It is another schematic sectional drawing for demonstrating a preferable reduction | restoration part.

  The present invention will be described with reference to three embodiments.

<Aspect 1>
The present invention provides a reduction step for reducing sterilizing active ingredients in raw water to obtain reduced water, an ion exchange step for removing anions contained in the reduced water to obtain anion exchange treated water, and the anions. A water treatment method comprising a reverse osmosis membrane treatment step of obtaining permeated water by treating exchange-treated water with a reverse osmosis membrane.
Hereinafter, such a water treatment method is also referred to as “mode 1”.

Aspect 1 will be described with reference to the drawings.
FIG. 1 is a conceptual diagram of a water treatment apparatus capable of implementing the first aspect.
In FIG. 1, a water treatment apparatus 10 receives raw water 13, reduces a sterilizing active component contained in the raw water 13 and discharges the reduced water 15, and accepts the reduced water 15 and the negative water contained in the reduced water 15. Ion exchange part 14 which removes ions and discharges anion exchange treated water 17 and reverse osmosis membrane treatment part 16 which treats anion exchange treated water 17 with a reverse osmosis membrane and discharges permeate 19 .

In the aspect 1, it is preferable to treat the raw water 13 containing the sterilizing active ingredient and the anionic ingredient on the basis of sterile water.
For example, in a beverage factory, before filling a plastic bottle with a product liquid, chemicals based on hydrogen peroxide or peracetic acid (for example, 0.5% by mass of peracetic acid, 0.5% by mass of acetic acid, peroxide) An operation of washing the inner surface with aseptic water heat-treated at high temperature is performed after spraying and sterilizing the inner surface of the PET bottle with 1% by mass of hydrogen). And by such operation, the waste_water | drain containing a disinfection active ingredient (hydrogen peroxide, peracetic acid, etc.) and an anion component (acetic acid etc.) is discharged | emitted.
By treating such waste water (raw water) by the water treatment method according to aspect 1 of the present invention, permeated water from which all of the sterilizing active ingredients and anion components contained in the waste water (raw water) are removed can be obtained. . In the water treatment method according to aspect 1 of the present invention, the water treatment is carried out while suppressing the growth of bacteria. Therefore, the increase in microorganisms in the permeated water obtained by permeating the reverse osmosis membrane, and the reverse osmosis membrane fouling caused by bacteria. The ring can be suppressed, and as a result, the operating rate of the water treatment apparatus using this method can be increased, the number of replacement of the reverse osmosis membrane can be reduced, and the operating cost can be reduced.

<Aspect 2>
The present invention includes an addition step of adding an ionic body-forming substance that forms an ionic body by combining with an uncharged organic substance that is an organic compound having no charge to raw water to obtain added water, and the added water is used as a reverse osmosis membrane. A reverse osmosis membrane treatment step for obtaining permeated water by treatment with a water treatment method.
Hereinafter, such a water treatment method is also referred to as “aspect 2”.

  In aspect 2, the same ion exchange part as in aspect 1 and aspect 3 described later may be provided. In this case, the ionic body-forming substance in the aspect 2 may be added to the raw water before being processed by the ion exchange part, or may be added to the raw water after being processed by the ion exchange part.

Aspect 2 will be described with reference to the drawings.
FIG. 2 is a conceptual diagram of a water treatment apparatus that can implement the second embodiment.
In FIG. 2, the water treatment apparatus 20 includes an adding means 18 that adds an ionic body forming substance that forms an ionic body by combining with an uncharged organic substance that is an organic compound having no charge to the raw water 23 to obtain added water 26. The reverse osmosis membrane treatment unit 16 obtains the permeated water 29 by treating the added water 26 with a reverse osmosis membrane.

In the aspect 2, it is preferable to treat the raw water 23 containing uncharged organic matter (formaldehyde or the like) which is an organic compound having no charge, based on sterile water.
For example, in a beverage factory, before filling a plastic bottle with a product liquid, chemicals based on hydrogen peroxide or peracetic acid (for example, 0.5% by mass of peracetic acid, 0.5% by mass of acetic acid, peroxide) An operation of washing the inner surface with aseptic water heat-treated at high temperature is performed after spraying and sterilizing the inner surface of the PET bottle with 1% by mass of hydrogen). And by such operation, the waste_water | drain containing the said uncharged organic substance represented by formaldehyde is discharged | emitted.
By treating such waste water (raw water) by the water treatment method of aspect 2 in the present invention, permeated water from which uncharged organic substances such as formaldehyde contained in the waste water (raw water) are also removed can be obtained.

<Aspect 3>
The present invention includes all the configurations included in the aspect 1, and further converts an ionic body forming substance that forms an ionic body by combining with an uncharged organic substance having no charge into the reduced water and / or the anion exchange treated water. The water treatment method includes an addition step of adding, and the permeated water from which the non-charged organic matter is removed in the reverse osmosis membrane treatment step is obtained.
Hereinafter, such a water treatment method is also referred to as “aspect 3”.

Aspect 3 will be described with reference to the drawings.
FIG. 3 is a conceptual diagram of a water treatment apparatus that can implement the third embodiment.
In FIG. 3, the water treatment device 30 receives the raw water 33, reduces the sterilizing active component contained in the raw water 33 and discharges the reduced water 15, and receives the reduced water 15 and the negative water contained in the reduced water 15. An ion exchange part 14 that removes ions and discharges the anion exchange treated water 17 and an ion forming substance that forms an ionic body by combining with an uncharged organic substance having no charge are added to the anion exchange treated water 17 And a reverse osmosis membrane treatment unit 16 for treating the added water 26 obtained by adding the ion-forming substance to the anion exchange treated water 17 with a reverse osmosis membrane and discharging the permeated water 39. .
Here, the ion-forming substance may be added to the reduced water 15 instead of the anion exchange treated water 17, or may be added to both the reduced water 15 and the anion exchange treated water 17.

In the aspect 3, it is preferable to treat the raw water 33 containing the sterilizing active ingredient and the anionic ingredient and further containing an uncharged organic substance such as formaldehyde on the basis of sterile water.
For example, in a beverage factory, before filling a plastic bottle with a product liquid, chemicals based on hydrogen peroxide or peracetic acid (for example, 0.5% by mass of peracetic acid, 0.5% by mass of acetic acid, peroxide) An operation of washing the inner surface with aseptic water heat-treated at high temperature is performed after spraying and sterilizing the inner surface of the PET bottle with 1% by mass of hydrogen). And by such operation, the waste_water | drain containing uncharged organic substances, such as a disinfection active ingredient (hydrogen peroxide, peracetic acid, etc.), an anion component (acetic acid, etc.), and formaldehyde, is discharged | emitted.
By treating such waste water (raw water) by the water treatment method of aspect 3 in the present invention, it is possible to obtain permeated water from which all sterilizing active ingredients and anion components contained in the waste water (raw water) have been removed. Further, in the water treatment method according to aspect 3 of the present invention, water treatment is performed while suppressing the growth of bacteria. Therefore, the increase in bacteria in the permeated water obtained by permeating the reverse osmosis membrane, and further fouling of the reverse osmosis membrane by bacteria. As a result, the operating rate of the water treatment device using this method can be increased, the number of replacement of the reverse osmosis membrane can be reduced, and the operating cost can be reduced.
Moreover, in addition to the sterilizing active ingredient and the anion component contained in the waste water (raw water), uncharged organic substances such as formaldehyde are also removed by treating such waste water (raw water) by the water treatment method of aspect 3 in the present invention. Therefore, when the water is reused again as sterile water, the water recovery rate of the water treatment device can be set high because formaldehyde, etc., which is also stipulated in the drinking water standards for tap water, does not concentrate in the permeated water. Water treatment costs at beverage factories can be greatly reduced, and environmental contributions can be greatly improved.

  Next, each part with which each water treatment apparatus which can implement the aspects 1-3 is provided is demonstrated.

<Reduction part>
In the water treatment device 10 of the aspect 1 and the water treatment device 30 of the aspect 3, the reducing unit 12 is not particularly limited as long as it has a reducing ability to reduce and decompose the sterilizing active ingredient (oxidant) contained in the raw water. For example, a reaction tank filled with a reducing agent can be mentioned. Examples of the reducing agent include activated carbon, iron compounds, and metal catalysts (platinum, palladium, manganese, etc.), and a supported catalyst in which these are supported on a carrier can also be used. By passing through the inside of the reaction tank filled with such a reducing agent, the sterilizing active ingredient (oxidizing agent) contained in the raw water can be reduced and decomposed.

  When a reaction tank filled with a reducing agent is used as the reducing portion, the linear velocity is preferably 10 to 30 m / hr, and more preferably 10 to 20 m / hr.

  For example, when wastewater containing peracetic acid, acetic acid and hydrogen peroxide discharged from a beverage factory is treated as raw water, the peracetic acid is acetic acid by reducing the raw water through a reducing part such as by passing the raw water through the reducing part. Thus, hydrogen peroxide is decomposed into water and oxygen. In this case, since the sterilizing active ingredient is not included in the reducing water discharged from the reducing unit, bacteria are likely to propagate on the downstream side of the reducing unit.

In the water treatment apparatus of the present invention, the reducing unit is a reducing device having a first reaction tank and a second reaction tank filled with a reducing agent, and a communication part connecting the upper ends of these tanks, The raw water is passed upwardly into the first reaction tank, and the raw water that has flowed out from the upper end of the first reaction tank is caused to flow into the second reaction tank through the communication part, and the second reaction is performed. In the tank, the raw water is passed downward to obtain the reduced water discharged from the lower part of the second reaction tank [α], and the raw water is passed upward into the second reaction tank. The raw water flowing out from the upper end of the second reaction tank is caused to flow into the first reaction tank through the communication part, and the raw water is allowed to flow downward in the first reaction tank. Two treatments with the treatment [β] for obtaining the reduced water discharged from the lower part of one reaction tank can be performed alternately. It is preferable that it is comprised so that it can do.
Such a reduction device will be described in detail with reference to FIGS.

FIG. 4 shows a preferred embodiment of the reduction section in the water treatment apparatus of the present invention, in which a partition plate 42 is installed in a vertical direction in a bottomed outer cylinder 41 placed vertically, and the outer cylinder 41 is formed by the partition plate 42. The interior is divided into a first water passage 43 and a second water passage 44. A space 47 exists above the partition plate 42 in the outer cylinder 41.
Then, the reducing agent 50 is filled into the first water passage 43 to form a first reaction tank 51, and the reducing agent 50 is filled into the second water passage 44 to form a second reaction tank 52. The space 47 serves as a communication part that connects the upper ends of the first reaction tank 51 and the second reaction tank 52. The space 47 is preferably not a sealed space but a hole connected to the outside of the system. This is because the gas generated by the raw water passing through the first reaction tank 51 can escape from the system.
Pipes 53 and 54 are connected to the bottom of the first reaction tank 51 and the bottom of the second reaction tank 52, respectively.

  In such a reduction device 40, when raw water is continuously supplied from the bottom into the first reaction tank 51 through the pipe 53, the raw water flows upward in the first reaction tank 51 and reaches the upper end of the first reaction tank 51. Reach. And raw | natural water flows out from an upper end part, and flows in in the 2nd reaction tank 52 through the space 47. FIG. Further, the raw water flows downward in the second reaction tank 52, passes through the second reaction tank 52, and then is discharged from the pipe 54 below the second reaction tank 52.

  The raw water is passed upward into the first reaction tank, and the raw water that has flowed out from the upper end of the first reaction tank is caused to flow into the second reaction tank through the communication portion, The process of obtaining the reduced water discharged from the lower part of the second reaction tank by passing the raw water downward in the second reaction tank is referred to as “treatment [α]”.

  According to such a treatment [α], the reducing agent flows in the first reaction tank 51 due to the upward flow, so that the contact between the reducing agent and the raw water is promoted, and the sterilizing active ingredient in the raw water is reduced. Can be performed efficiently. Moreover, since the raw | natural water after passing the 1st reaction tank 51 has the density | concentration of a disinfection active ingredient very low, the generation amount of the gas in the 2nd reaction tank 52 is relatively small. Therefore, the raw water and the reducing agent come into close contact with each other by flowing downward into the second reaction tank 52 that is densely filled with the reducing agent, and the sterilizing effect that remains slightly decomposed in the first reaction tank 51 The components can be reduced more completely.

  4 can continuously supply the raw water from the bottom into the second reaction tank 52 through the pipe 54, as shown in FIG. Then, the raw water flows upward in the second reaction tank 52 and reaches the upper end of the second reaction tank 52. And raw | natural water flows out from an upper end part, and flows in in the 1st reaction tank 51 through the space 47. FIG. Further, the raw water flows downward in the first reaction tank 51, passes through the first reaction tank 51, and then is discharged from the pipe 53 below the first reaction tank 51.

  The raw water is passed upward into the second reaction tank, and the raw water that has flowed out from the upper end of the second reaction tank is caused to flow into the first reaction tank through the communication portion, The process of obtaining the reduced water discharged from the lower part of the first reaction tank by passing the raw water downward in the first reaction tank is referred to as “treatment [β]”.

When such treatment [β] is performed, it is possible to suppress the growth of bacteria in the second reaction tank 52.
If only the above-mentioned process [α] is continued for a long time, there is a possibility that bacteria grow in the second reaction tank 52. In the treatment [α], since most of the sterilizing active ingredients in the raw water are reduced and decomposed by passing the first reaction tank 51 upward, the raw water flowing into the second reaction tank 52 This is because the sterilizing active ingredient is hardly contained.
Therefore, it is preferable to suppress the growth of bacteria in the first reaction tank 51 and the second reaction tank 52 by alternately performing the process [α] and the process [β] as described above.

<Ion exchange part>
In the water treatment device 10 according to the aspect 1 and the water treatment device 30 according to the aspect 3, the ion exchange unit 14 is particularly limited as long as it can remove anions contained in the reduced water 15 and discharge the anion exchange treated water 17. Not. For example, an anion exchange resin (anion exchange resin) can be preferably applied. In addition, an electric desalination apparatus can be used as the ion exchange unit.

For example, when wastewater containing peracetic acid, acetic acid, and hydrogen peroxide based on sterile water discharged from a beverage factory is treated as raw water, the reduced water discharged from the reducing section contains negatively charged acetate ions. (CH ₃ COO ⁻ ) is included. When such reduced water is treated with, for example, an anion exchange resin, caustic soda is generated from the cation (Na ^+, etc.) contained in sterile water and the hydroxide ion when the anion exchange resin exchanges anions. The anion-exchanged water is alkaline (for example, pH is about 9 to 11) and is water-treated while suppressing the growth of bacteria on the surface of the reverse osmosis membrane. Therefore, the permeation obtained by allowing the reverse osmosis membrane to permeate. It is possible to suppress the increase of bacteria in water and the fouling of reverse osmosis membranes by bacteria.

<Adding means>
The addition means 18 in the water treatment apparatus 20 of aspect 2 and the water treatment apparatus 30 of aspect 3 is not particularly limited as long as it can add an ion-forming substance described later to the raw water 23 or the ion exchange water 17. For example, in the case of a liquid ion-forming substance, this is stored in a conventionally known storage tank connected to a pipe, and the pump is operated to discharge the ion-forming substance from the inside of the storage tank through the pipe. Or the thing of the aspect added to the anion exchange process water 17 is mentioned. Furthermore, it is preferable to store the raw water 23 or the anion exchange treated water 17 in a tank, add the ion-forming substance to the tank, and then mix the inside of the tank. Even when a powdery ionic body-forming substance is used, this is stored in a conventionally known hopper, and the ionic body-forming substance is cut out from a cutting device installed at the lower part of the hopper, and raw water 23 or anion exchange treated water is used. 17 can be added.

The uncharged organic substance contained in the raw water 23 or the anion exchange treated water 17 is preferably an organic compound having no charge and having 3 or less C atoms. The uncharged organic substance is more preferably an organic compound having an aldehyde group, a carboxyl group or a hydroxyl group, and further preferably an organic compound having an aldehyde group.
Specific examples of the uncharged organic substance include formaldehyde and acetaldehyde. The uncharged organic substance is preferably formaldehyde.

The ionic body-forming substance added by the adding means forms an ionic body by combining with an uncharged organic substance as described above.
Here, an ionic body means a compound having a charge in an aqueous solution.
As the ion-forming substance, an inorganic salt is preferably used, sodium sulfite, sodium bisulfite or sodium bisulfite is more preferably used, and sodium sulfite is further preferably used.

For example, when the uncharged organic substance is formaldehyde and sodium sulfite is used as the ion-forming substance, it is considered that formaldehyde and sodium sulfite are combined to form CH ₂ (OH) SO ₃ ^— . Since such ionic bodies are easily captured by the ion exchange part or reverse osmosis treatment part, they can be easily separated and removed from the raw water (added water 26, reduced water 15 or anion exchange treated water 17). .

  Further, as described above, the anion exchange treated water discharged from the ion exchange section is alkaline (for example, alkaline having a pH of about 9 to 11). Since the added water 26 retains alkalinity, bacteria are unlikely to propagate like the anion exchange treated water.

<Reverse osmosis membrane processing section>
In the water treatment device 10, the water treatment device 20, and the water treatment device 30 of the first, second, and third embodiments, the reverse osmosis membrane treatment unit 16 treats the anion exchange treated water 17 or the added water 26 with the reverse osmosis membrane. And if it is a site | part from which the permeated water 19, 29, 39 is obtained, it will not specifically limit.
As the reverse osmosis membrane (RO membrane), for example, a conventionally known membrane can be used.

For example, the sterilized water used in a beverage factory contains a cationic component such as Na ⁺ which can be separated and removed by a reverse osmosis membrane. Even if bacteria are present in the anion exchange treated water, they can be separated and removed by the reverse osmosis membrane. Moreover, in the case of the aspect (aspect 2 and aspect 3) provided with an addition means, the ionic body formed by combining the uncharged organic substance and the ionic body forming substance is captured by the reverse osmosis treatment unit, and the raw water (added water 26, reduced) It can be easily separated and removed from the water 15 or the anion exchange treated water 17).

<Experiment 1>
Raw water was treated using the water treatment apparatus 10 shown in FIG. Raw water is obtained by adding hydrogen peroxide, peracetic acid or the like to pure water. The composition of raw water is shown in Table 1.
In addition, a reaction tank filled with activated carbon (Evadia LG-10SC, manufactured by Mizu-ing Co., Ltd.) is used as the reducing unit, the space velocity (LV, linear velocity) is 15 m / hr, and the superficial velocity (SV) is 15 / hr. The raw water was passed through the reaction tank.
In addition, an anion tower equipped with a strongly basic anion exchange resin (Dowex Marathon A) is used as the ion exchange part, the space velocity (LV, linear velocity) is 30 m / hr, and the superficial velocity (SV) is 30 / hr. Reduced water was passed through.
Further, in the reverse osmosis membrane treatment section, the RO membrane was ES20 manufactured by Nitto Denko Corporation. Moreover, the water flow pressure was processed as 0.7 MPa.

And peracetic acid concentration (mg / L), acetic acid concentration (mg / L), Na concentration (mg / L), viable cell count (CFU / mL) in each of reduced water, anion exchange treated water and permeated water, The pH was measured.
The measurement results are shown in Table 1.

  As shown in Table 1, permeated water from which bacteria, sterilizing active ingredients, anionic components and cationic components were removed could be obtained. Moreover, since there was no site | part with neutral pH in all the processes, it was able to process, suppressing the proliferation of bacteria, and to suppress the fouling of the reverse osmosis membrane by bacteria.

<Experiment 2>
Raw water was treated using the water treatment apparatus 20 shown in FIG. Raw water is obtained by adding formaldehyde to pure water at 0.5 mg / L.
After formaldehyde was added, sodium sulfite was further added to 10 ppm, and the mixture was stirred for 10 minutes and mixed, and then treated with an RO membrane. The RO membrane used was AG2521TM manufactured by OSMONICS, and the RO recovery rate was 90%. Moreover, the water temperature of the process target water at the time of processing by RO membrane was 35 degreeC.

And the density | concentration (mg / L) of formaldehyde in each of addition water and permeated water was measured.
The measurement results are shown in Table 2.

  As shown in Table 2, permeated water from which formaldehyde was removed could be obtained.

10, 20, 30 Water treatment device 12 Reduction unit 13, 23, 33 Raw water 14 Ion exchange unit 15 Reduced water 16 Reverse osmosis treatment unit 17 Anion exchange treated water 18 Addition means 19, 29, 39 Permeated water 26 Added water 40 Reduction Device 41 Outer cylinder 42 Partition plate 43 First water passage 44 Second water passage 47 Space 50 Reducing agent 51 First reaction tank 52 Second reaction tank 53, 54 Pipe

Claims (4)

A reduction step of reducing the bactericidal active ingredient in the raw water to obtain reduced water;
An ion exchange step of removing anion contained in the reduced water to obtain anion exchange treated water;
A reverse osmosis membrane treatment step of obtaining permeated water by treating the anion exchange treated water with a reverse osmosis membrane,
The reduction step comprises
Using a reducing device comprising a first reaction tank and a second reaction tank filled with a reducing agent, and a communicating part connecting the upper ends of these tanks,
The raw water is passed upwardly into the first reaction tank, and the raw water that has flowed out from the upper end of the first reaction tank is caused to flow into the second reaction tank through the communication part, and the second reaction is performed. In the tank, the raw water is passed downward to obtain the reduced water discharged from the lower part of the second reaction tank [α],
The raw water is allowed to flow upward into the second reaction tank, and the raw water that has flowed out from the upper end of the second reaction tank is caused to flow into the first reaction tank through the communication portion, so that the first reaction is performed. In the tank, the raw water is passed downward, and the process [β] for obtaining the reduced water discharged from the lower part of the first reaction tank is alternately performed. An addition step of adding an ionic body-forming substance that forms an ionic body by combining with an uncharged organic substance that is an organic compound having no charge to the reduced water and / or the anion exchange treated water;
The water treatment method according to claim 1, wherein in the reverse osmosis membrane treatment step, the permeated water from which the uncharged organic matter is further removed is obtained. A reducing part that reduces the sterilizing active ingredient in the raw water and discharges the reduced water;
An ion exchange unit that receives the reduced water, removes anions contained in the reduced water, and discharges the anion exchange treated water;
A reverse osmosis membrane treatment section for treating the anion exchange treated water with a reverse osmosis membrane and discharging permeated water,
The reducing part is
A reduction device having a first reaction tank and a second reaction tank filled with a reducing agent, and a communication part connecting the upper ends of these tanks,
The raw water is passed upwardly into the first reaction tank, and the raw water that has flowed out from the upper end of the first reaction tank is caused to flow into the second reaction tank through the communication part, and the second reaction is performed. In the tank, the raw water is passed downward to obtain the reduced water discharged from the lower part of the second reaction tank [α],
The raw water is allowed to flow upward into the second reaction tank, and the raw water that has flowed out from the upper end of the second reaction tank is caused to flow into the first reaction tank through the communication portion, so that the first reaction is performed. In the tank, the raw water is passed downward and the process [β] for obtaining the reduced water discharged from the lower part of the first reaction tank can be alternately performed. Water treatment equipment. An addition means for adding an ionic body-forming substance that forms an ionic body by combining with an uncharged organic substance that is an organic compound having no charge to the reduced water and / or the anion exchange treated water;
The water treatment device according to claim 3, wherein the reverse osmosis membrane treatment unit further obtains the permeated water from which the uncharged organic substances are removed.

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